1. Field of the Invention
The present invention relates to an apparatus for automatically and periodically operating an aerosol container in discreet dispense cycles to discharge a metered quantity of the container's contents. More particularly, the invention relates to a device incorporated in this apparatus for stopping operation of the container and for indicating when it has been emptied.
Pressurized aerosol containers are widely used to dispense various consumer products such as room deodorizers, insecticides, germicides and the like. These containers typically include an internally mounted valve connected to an outwardly projecting valve stem which carries a fluid atomizing nozzle. Inward depression or tilting of the valve stem opens the valve to discharge contents of the container as a fine spray through the nozzle. The valve may be of the type that discharges contents of the container as long as it is held open, or may only discharge a metered quantity every time it is operated.
Non-pressurized containers which dispense consumer products are also available. These containers are typically equipped with a pump, of either of the "throttling" or "non-throttling" type, having a plunger which carries a nozzle. When the plunger is depressed, the container's contents are discharged as a fine spray. If the pump is of the "non-throttling" type, discharge only occurs after a predetermined pressure has been developed thereby. If the pump is of the "throttling" type, discharge occurs as soon and as long as it is operated.
The term "aerosol" is usually used to identify containers of the pressurized type described above and is not ordinarily applied to non-pressurized containers equipped with a pump. However, the apparatus and device of the present invention may be used equally well with either type container. Therefore, as used in this specification and the concluding claims, the term "aerosol" is intended to include both pressurized containers equipped with valves, non-pressurized containers equipped with pumps or any other container which includes a mechanism operable to discharge contents of the container by being depressed inwardly or by being tilted.
2. Description of the Prior Art
Products such as room deodorizers, insecticides and germicides, are most effective when dispensed periodically into the air and distributed uniformly in the area they are intended to treat. Therefore, various devices have been proposed which automatically and periodically operate aerosol containers of these products. One such device, disclosed in U.S. Pat. No. 3,739,944 (Rogerson), includes a DC motor coupled through a reduction gear train and lever to the nozzle and further, the valve of an aerosol container. A timing circuit, which connects the motor to a power supply, delivers periodic pulses of power which energize the motor to thereby operate the aerosol valve. The timing circuit includes a resistance-capacitance (RC) charging network having a discharge path through a unijunction. Accordingly, when the charge on the capacitor in the RC network exceeds the trigger level of the unijunction, an energizing pulse is delivered to the motor. However, when the capacitor is discharged to a minimum level the pulse terminates. Further, the time required to charge the capacitor determines the periodicity of operation of the container. The time required to discharge the capacitor is selected to be sufficient to operate the aerosol valve, when its inertia and mechanical resistance to operation are considered.
Other devices for automatically and periodically operating an aerosol container are disclosed in U.S. Pat. Nos. 3,779,425 (Werner); 3,726,437 (Siegel); 3,589,563 (Carragan et al.); 3,584,766 (Hart et al.); 3,187,949 (Mangel); and 3,018,056 (Montgomery). However, none of the patents reviewed above discloses apparatus for automatically stopping operation of the container when empty or for indicating when the container is empty.